1. Field of the Invention
The present invention relates to novel polymer containing polyol compositions; and more particularly, to an improved infused polymer containing polyol prepared by infusion of certain polymerizable monomers onto unsaturation sites of an oxyalkadienyl containing polyol.
2. Prior Art
"Polyurethane" is generally descriptive of a broad class of polymeric materials which contain numerous urethane linkages throughout the structure. Such materials are produced by the reaction of a material containing one or more free isocyanate moieties with a material containing one or more active hydroxyl groups. The interaction of a free isocyanate with an active hydroxy yields a urethane linkage.
Polyurethane compositions are conventionally prepared by the use of a polyfunctional free isocyanate containing material and a polyfunctional hydroxyl containing material such as a polyester or polyether polyol. The polyfunctionality of the reactants provides cross-linking which strengthens the material.
It has been disclosed that the polyfunctional hydroxy containing materials dispersed in a polymer medium are effective in producing superior polyurethane foams. These mixtures have become known in the art as polymer polyols and are sometimes referred to as graft polymers. Examples of such compositions and their use are found in U.S. Pat. No. 3,383,351.
These graft polyols are formed by the in situ polymerization of a monomer in the presence of a saturated polyol medium. Purportedly, during the reaction, one or more of the monomers is "grafted" to the saturated polyol constituent by displacement of a hydrogen with the resultant formation of the covalent bond. The actual occurrence of this grafting of monomer to polyol containing chain has been shown slight in relation to the formation of the vinyl polymer. Thus, these polymer/polyols are in actuality an intimate admixture.
Purportedly the utilization of these polymer/polyol mixtures in urethane formulations yields polyurethane compositions having certain desirable physical properties while providing a plurality of active hydroxy sites for crosslinking the nucleus of the polyol constituent into the polyurethane network. However, the polymeric moiety is not bonded to the polyol moiety and thus not "chemically linked" into the resulting urethane composition.
Attempts to chemically bond or infuse the polymeric constituent into the polyol molecule have not generally met with success. One method involves the introduction of ethylenic unsaturation into the polyol structure by reaction of a polyhydric initiator with an organic compound having both ethylenic unsaturation and a reactive functional group such as hydroxyl or carboxyl. See, for example, U.S. Pat. No. 3,652,639.
These compounds are generally prepared by reacting dicarboxyl terminated moieties containing ethylenic unsaturation or a moiety containing both an epoxide and ethylenic unsaturation with a polyol. When an epoxide is used, the ring opening reaction yields a secondary hydroxy. Upon alkoxylation to produce the very desirable polyether product, the secondary alcohols do not alkoxylate readily.
When the dicarboxyl containing material or the corresponding anhydride is utilized, crosslinking can occur. Specifically, the reaction carboxyl group can react with for example two hydroxy moieties on a single polyol molecule producing a "cyclic" type product. Thus, hydroxy moieties contained within this cyclic structure can be hindered in the subsequent isocyanate reaction. Additionally, since the carboxyl containing moiety is difunctional, it can act as a crosslinking agent to tie two polyol containing compounds together. This increases viscosity, reduces functionality, and can produce a solid product if the conditions are not carefully controlled. The carboxyl/hydroxy linkages formed are esters which cannot be readily alkoxylated. Further, remaining unreacted carboxyl groups must be esterified by use of an alcohol.
It has now been found that a novel class of polymer containing polyols which are better characterized as infused polymer containing polyols exhibit exceptional stability, do not undergo large viscosity changes upon prolonged storage, have an exceptionally high portion of polymerized monomer fused into the polyol structure and can be readily alkoxylated. One outstanding advantage is that single chain substitutent carries two ethylenic unsaturated sites to the polyol molecule. Additionally, these compounds do not contain a second functional group on the unsaturation containing chain and thus will not crosslink or cyclize during preparation.